cm:Member: us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetGainLossIncludingPortionAttributableToNoncontrollingInterestMember
       
          
          | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member] | 
       
       
          
          | us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetGainLossIncludingPortionAttributableToNoncontrollingInterestMember | 
       
       
          
          | Accumulated other comprehensive income (loss) related to gain (loss) component of defined benefit plans including the portion attributable to the noncontrolling interest. | 
       
       
          
          | cm:Member | 
       
       
          
          | [Member] (nonnum:domainItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | true | 
       
       
          
          | us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetGainLossIncludingPortionAttributableToNoncontrollingInterestMember |